Sputtering, also known as physical vapor deposition (PVD), is a method of forming features in integrated circuits and is generally performed in a process chamber. Sputtering deposits a material layer such as a dielectric material on a workpiece (e.g., a wafer). A source material, such as a target, is bombarded by ions strongly accelerated by an electric field. The ion bombardment causes the material to be ejected from the target and causes the material to collect on, or be deposited upon, the substrate (e.g., the workpiece). During deposition, ejected particles may also be deposited upon other surfaces such as a shield or other inner surfaces of the process chamber.
The unwanted coating of the shield may cause defects to occur in the wafer being processed, or cause defects in subsequent wafer processing. Defects can occur, for example, when unwanted deposition occurs on the shield and a charge accumulates on the unwanted deposition causing arcing, or dielectric material collecting on the shield peels off.
Thus, the inventors have provided embodiments of an improved target for reducing defects during dielectric sputtering.